ML18100A727

LER 93-012-00:on 931030,TS 3.0.3 Entered Due to Inoperability of 21 Bast Level Indication While 22 Bast Out of Svc.Caused by Design Deficiency.Design Change Installed. W/931123 Ltr

ML18100A727
Person / Time
Site:	Salem
Issue date:	11/23/1993
From:	Pastva M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-012-01, LER-93-12-1, NUDOCS 9312060021
Download: ML18100A727 (6)

Text

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OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station November 23, 1993

• u. s. Nuclear Regulatory commission Document Control Desk

. Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75

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*--- -DOCKET. N0 *.. 50~311 -- - ---- --

UNIT NO. 2 LICENSEE EVENT REPORT 93-012-00 This Licensee Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a) (2) (i) (B).

This report is required to be issued within thirty (30) days of event discovery.

Sincerely yours,

c. A. Vondra General Manager -

Salem Operations MJPJ:pc Distribution

~~~2060021 931123 S ADOCK 05000311 PDR The power is in your hands.

95-2189 REV 7-92

NRC FORM 3i;& U.S. NUCLEAR REGULATORY COMMISSION (6-891 APPROVED OMB NO. 3150-0104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-5301, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO .

THE PAPERWORK REDUCTION PROJECT (3150-01041, OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

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FACILITY NAME (1) DOCKET NUMBER (2)

Salem Generating Station - Unit 2 TITLE (41 o I s I o I o I o I 31 1 11 1 loF o I 5 T/S 3.0.3 Entry; Inoperability of 21 BAST Level Indication While 22 BAST Out of Service.

_EVENT DATE (6) LER NUMBER (61 REPORT DATE (71 OTHER FACILITIES INVOLVED (Bl MONTH DAV YEAR VEAR  :]( SE~~~~~~AL tt ~~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISI 1 Io 3 I o 9 3 91 *3 - oI1 I 2 - o I o 1 I1 I 2 3 9 I3

. OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE Rt,QUIREMENTS OF 10 CFR §: ICh*ck ons or mora of th* followin1111111 MODE Ill 1

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LICENSEE CONTACT FOR THIS LER (121

&0.7311112llvillllBI 60.731111211*1 NAME TELEPHONE NUMBER AREA CODE M. J. Pastva, Jr. - LER Coordinator 6 10 9 3 13 I 91- I 51116 I 5 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 1131 MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT SYSTEM COMPONENT TUR ER TUR ER I I I I I I I I I I I I I I I I I I I I I I I I I I I I SUPPLEMENTAL REPORT EXPECTED (141 MONTH DAY YEAR EXPECTED n YES (If y11, comp/*!* EXPECTED SUBMISSION OATEI k-i NO ABSTRACT (Limit to 1400 spac11s. i.t1.* approxim1t11ly fifteen singl11-spsc11 typ11writt11n lin111} (161 SUBMISSION DATE 1151 I I I At 0901 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.428305e-4 months <br /> on 10/30/93, 21 Boric Acid Storage Tank (BAST) level indicator was declared inoperable due to false level indication. At the time, 22 BAST was out of service therefore, Technical Specification (TS) Table 3.3-11, Action 3, was not met, and TS 3.0.3 was entered. TS 3.0.3 was exited, at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> (same day), upon return of 22 BAST to normal lineup. This event resulted from boron blockage in 21 BAST level indicator bubbler tube. The tube was blown down and at 1051 hours0.0122 days <br />0.292 hours <br />0.00174 weeks <br />3.999055e-4 months <br /> (same day), 21 BAST was returned to service.

The root cause of this event is design of the BAST level indication system. A design change, including reducing the BAST boron concentration to 4% to minimize boron precipitation in the tank level indicator bubbler tube, is being installed during the current Unit 1 refueling outage and is scheduled for installation on Unit 2.

NRC Form 366 16-891

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-012-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are shown in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

Technical Specification 3.0.3 Entry; Inoperability of 21 Boric Acid Storage Tank (BAST) Level Indication While 22 BAST Out of Service

.Event_Dates: _10/30/-93 Report Date: 11/23/93 This report was initiated by Incident Report Nos.93-440. This event is reportable to the NRC per lOCFR 50.73(a) (2) (i) (B) due to entering Technical Specification (TS) 3.0.3.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% - Unit Load 1170 MWe 22 BAST was out of service in support of boron batching operations.

DESCRIPTION OF OCCURRENCE:

At 0901 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.428305e-4 months <br /> on October 30, 1993, the level indicator of 21 BAST {CB}

was declared inoperable due to false level indication. Since 22 BAST was out of service, Action 3 of TS Table 3.3-11 was not met, and action associated with TS 3.0.3 was entered.

TS 3.0.3 was exited, at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> (same day), upon return of 22 BAST to normal lineup.

In MODES 1, 2, AND 3, TS 3.3.3.7 requires two (2) OPERABLE BAST solution level indicators (one/tank). With one level indicator inoperable, Action 3 of TS Table ~.3-11 applies:

"With the number of OPERABLE channels one less than the Required Number of Channels shown in TS Table 3.3-11, operation may proceed provided that the Boric Acid Tank associated with the remaining OPERABLE channel satisfies all requirements of TS 3.1.2.8.a."

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• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-012-00 3 of 5 DESCRIPTION OF OCCURRENCE: (cont'd)

TS 3.1.2.8 states:

"Each of the following borated water sources shall be OPERABLE:

a. A boric acid storage system and at least one associated heat tracing system with:

1. A minimum contained volume of 5106 gallons,

2. Between 20,000 and 22,500 ppm of boron, and,

3. A minimum solution temperature of 145°F.

b. The refueling water storage tank with: "

TS 3.0.3 states:

"When a Limiting Condition for Operation is not met except as provided in the associated ACTION requirements, within one hour action shall be initiated to place the unit in a MODE in which the specification does not apply by placing it, as applicable, in:

1. At least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />,

2. At least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and

3. At least COLD SHUTDOWN within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Where corrective measures are completed that permit operation under the ACTION requirements, the ACTION may be taken in accordance with the specified time limits as measured from the time of failure to meet the Limiting Condition of Operation.

Exceptions to these requirements are stated in the individual specifications."

ANALYSIS OF OCCURRENCE:

The BAST (with the transfer pumps) are part of the boration subsystem of the Chemical and Volume Control System (CVCS). This subsystem ensures negative reactivity control during each mode of facility operation. Required components include two (2) borated water sources, two (2) BASTS and the Refueling Water Storage Tank (RWST).

Either BAST contains sufficient volume to support one cold shutdown with the most reactive control rod withdrawn. These tanks contain 12 weight % boric acid maintained at a temperature of 175°F. The BAST level indicator sensing design employs a nitrogen flow bubbler tube, which opens near the tank bottom, and another tube which opens near the tank top. Resultant differential pressure between the tubes is

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• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-012-00 4 of 5 ANALYSIS OF OCCURRENCE: (cont'd) used to determine level.

Use of a bubbler in a 12% boric acid solution results in indication failures when boron precipitation within the bubbler blocks the flow of nitrogen. A contributing factor to the precipitation is lower than desirable temperature within the bubbler tube. (Boron precipitation occurs when the 22,000 ppm boron solution temperature decreases below 145° F.) Past corrective actions (addressed most recently by LER 272/93-015-00) include adjustments to the nitrogen flow rate, increasing the frequency of system blowdown to once every seven days, and use .of.Control Air for blowdown. In addition, the BASTs and respective bubbler tubes of both units have been inspected and cleaned as necessary. These actions have proven to be marginally effective. Communications with other utilities, regarding BAST level bubbler failures in a boron solution, indicate boron precipitation will be eliminated by using a 4% boric acid solution. A design change, which includes reducing the BAST boron concentration to 4% to help minimize boron precipitation in the tank level indicator bubbler tube, is scheduled to be implemented. A similar Unit 1 design change will also be implemented.

At approximately 0901 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.428305e-4 months <br /> on October 30, 1993, the level indication of 21 BAST failed. At the time 22 BAST was out of service for boric acid batching. Due to inoperability of 21 BAST level indication and pre-existing unavailability of 22 BAST, TS 3.0.3 was entered. At 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> (same day), 22 BAST was returned to service and TS 3.0.3 was exited.

The false level indication of 21 BAST resulted from boron blockage of the indicator bubbler tube, attributed to design of the BAST level indication system. The tube was blown down to reestablish indication and at 1051 hours0.0122 days <br />0.292 hours <br />0.00174 weeks <br />3.999055e-4 months <br /> (same day), 21 BAST was returned to service and action associated with TS 3.3.3.7 was exited.

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is "Design, Manufacturing, Construction/

Installation" per NUREG-1022, (Licensee Event Report system) of the BAST level indication system. The event resulted from boron blockage in the 21 BAST level indicator bubbler tube, while 22 BAST was out of service.

PREVIOUS OCCURRENCES:

The following LERs address TS 3.0.3 entries due to BAST level

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• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-012-00 5 of 5 PREVIOUS OCCURRENCES: (cont'd) indication events: 272/92-023-00; 272/93-003-00; 272/93-009-00; 272/93-015-00; and 311/93-003-00. The root cause of this most recent event is the same as identified in the referenced LERs.

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SAFETY SIGNIFICANCE:

This event did not affect the health and safety of the public.

Although 21 BAST level indication had failed required tank level was maintained and the associated Boric Acid Transfer pumps and valves were maintained in normal alignment for use if required. In

_________addition, __ during this_ event_the Refueling Water Storage Tarlk (RWST) remained available.

CORRECTIVE ACTION:

Following this event, the 21 BAST level indicator bubbler tube was blown down to remove blockage and level indication returned to its previous reading.

A design change, including reducing the BAST boron concentration to 4% to minimize boron precipitation in the tank level indicator bubbler tube, is being installed during the current Unit 1 refueling outage and is scheduled for installation on Unit 2.

General Manager -

Salem Operations MJPJ:pc SORC Mtg.93-103